The shock of Covid-19 hit in different ways for Xiao Wu, a 27-year-old Ph.D. student in Harvard’s public health school, and his academic adviser, biostatistician Francesca Dominici. Wu, a former national high school math champion in China, was shaken in January as he absorbed reports from his native country about Covid-19’s exponential spread. “Considering that infection rate, it was almost guaranteed this would be a global pandemic,” he said. “It was transmitted too fast.” But reality didn’t sink in for Dominici until she walked across Harvard Yard on March 10, the day the university sent students home. “These kids were crying,” she recalled. “They were sitting on the curb, literally, with their suitcases. I think that’s when I realized—gosh, this is bad. This is huge.” When Dominici went home, she saw her work—quantifying the health effects of pollution—in the stark new light of a respiratory illness that was likely […]